package org.iteye.bbjava.frame.work.utils;

/**
 * Copyright (c) 2005-2009 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id$
 */
import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.lang.StringUtils;
import org.apache.struts2.ServletActionContext;

/**
 * Struts2工具类.
 * 
 * 实现获取Request/Response/Session与绕过jsp/freemaker直接输出文本的简化函数.
 * 
 * @author calvin
 */
public class Struts2Utils {

        //-- header 常量定义 --//
        private static final String HEADER_ENCODING = "encoding";
        private static final String HEADER_NOCACHE = "no-cache";
        private static final String DEFAULT_ENCODING = "UTF-8";
        private static final boolean DEFAULT_NOCACHE = true;

//        private static ObjectMapper mapper = new ObjectMapper();

        //-- 取得Request/Response/Session的简化函数 --//
        /**
         * 取得HttpSession的简化函数.
         */
        public static HttpSession getSession() {
                return ServletActionContext.getRequest().getSession();
        }

        /**
         * 取得HttpSession的简化函数.
         */
        public static HttpSession getSession(boolean isNew) {
                return ServletActionContext.getRequest().getSession(isNew);
        }

        /**
         * 取得HttpSession中Attribute的简化函数.
         */
        public static Object getSessionAttribute(String name) {
                HttpSession session = getSession(false);
                return (session != null ? session.getAttribute(name) : null);
        }

        /**
         * 取得HttpRequest的简化函数.
         */
        public static HttpServletRequest getRequest() {
                return ServletActionContext.getRequest();
        }

        /**
         * 取得HttpRequest中Parameter的简化方法.
         */
        public static String getParameter(String name) {
                return getRequest().getParameter(name);
        }

        /**
         * 取得HttpResponse的简化函数.
         */
        public static HttpServletResponse getResponse() {
                return ServletActionContext.getResponse();
        }

        //-- 绕过jsp/freemaker直接输出文本的函数 --//
        /**
         * 直接输出内容的简便函数.

         * eg.
         * render("text/plain", "hello", "encoding:GBK");
         * render("text/plain", "hello", "no-cache:false");
         * render("text/plain", "hello", "encoding:GBK", "no-cache:false");
         * 
         * @param headers 可变的header数组，目前接受的值为"encoding:"或"no-cache:",默认值分别为UTF-8和true.
         */
        public static void render(final String contentType, final String content, final String... headers) {
                HttpServletResponse response = initResponseHeader(contentType, headers);
                try {
                        response.getWriter().write(content);
                        response.getWriter().flush();
                } catch (IOException e) {
                        throw new RuntimeException(e.getMessage(), e);
                }
        }

        /**
         * 直接输出文本.
         * @see #render(String, String, String...)
         */
        public static void renderText(final String text, final String... headers) {
                render(ServletUtils.TEXT_TYPE, text, headers);
        }

        /**
         * 直接输出HTML.
         * @see #render(String, String, String...)
         */
        public static void renderHtml(final String html, final String... headers) {
                render(ServletUtils.HTML_TYPE, html, headers);
        }

        /**
         * 直接输出XML.
         * @see #render(String, String, String...)
         */
        public static void renderXml(final String xml, final String... headers) {
                render(ServletUtils.XML_TYPE, xml, headers);
        }

        /**
         * 直接输出JSON.
         * 
         * @param jsonString json字符串.
         * @see #render(String, String, String...)
         */
        public static void renderJson(final String jsonString, final String... headers) {
                render(ServletUtils.JSON_TYPE, jsonString, headers);
        }

        /**
         * 直接输出JSON,使用Jackson转换Java对象.
         * 
         * @param data 可以是List<POJO>, POJO[], POJO, 也可以Map名值对.
         * @see #render(String, String, String...)
         */
        public static void renderJson(final Object data, final String... headers) {
                HttpServletResponse response = initResponseHeader(ServletUtils.JSON_TYPE, headers);
                try {
                        mapper.writeValue(response.getWriter(), data);
                } catch (IOException e) {
                        throw new IllegalArgumentException(e);
                }
        }

        /**
         * 直接输出支持跨域Mashup的JSONP.
         * 
         * @param callbackName callback函数名.
         * @param object Java对象,可以是List<POJO>, POJO[], POJO ,也可以Map名值对, 将被转化为json字符串.
         */
        public static void renderJsonp(final String callbackName, final Object object, final String... headers) {
                String jsonString = null;
                try {
                        jsonString = mapper.writeValueAsString(object);
                } catch (IOException e) {
                        throw new IllegalArgumentException(e);
                }

                String result = new StringBuilder().append(callbackName).append("(").append(jsonString).append(");").toString();

                //渲染Content-Type为javascript的返回内容,输出结果为javascript语句, 如callback197("{html:'Hello World!!!'}");
                render(ServletUtils.JS_TYPE, result, headers);
        }

        /**
         * 分析并设置contentType与headers.
         */
        private static HttpServletResponse initResponseHeader(final String contentType, final String... headers) {
                //分析headers参数
                String encoding = DEFAULT_ENCODING;
                boolean noCache = DEFAULT_NOCACHE;
                for (String header : headers) {
                        String headerName = StringUtils.substringBefore(header, ":");
                        String headerValue = StringUtils.substringAfter(header, ":");

                        if (StringUtils.equalsIgnoreCase(headerName, HEADER_ENCODING)) {
                                encoding = headerValue;
                        } else if (StringUtils.equalsIgnoreCase(headerName, HEADER_NOCACHE)) {
                                noCache = Boolean.parseBoolean(headerValue);
                        } else {
                                throw new IllegalArgumentException(headerName + "不是一个合法的header类型");
                        }
                }

                HttpServletResponse response = ServletActionContext.getResponse();

                //设置headers参数
                String fullContentType = contentType + ";charset=" + encoding;
                response.setContentType(fullContentType);
                if (noCache) {
                        ServletUtils.setNoCacheHeader(response);
                }

                return response;
        }

}